Sensitivity of the lateral flow urine lipoarabinomannan assay in ambulant adults with advanced HIV disease: data from the TB Fast Track study. (20th April 2020)

• Record Type: Journal Article
• Authors: Tlali, Mpho; Fielding, Katherine L; Karat, Aaron S; Hoffmann, Christopher J; Muravha, Tshifhiwa; Grant, Alison D; Charalambous, Salome
• Is Part Of: Transactions of the Royal Society of Tropical Medicine and Hygiene. Volume 114:Number 8(2020)
• Page Start: 556
• Page End: 560
• Publication Date: 2020-04-20
• Subjects: algorithms -- lipoarabinomannan -- South Africa -- TB -- TB diagnostic tests -- HIV; Tropical medicine -- Periodicals; 616.9883
• DOI: 10.1093/trstmh/traa018
• Languages: English
• ISSNs: 0035-9203

Abstract

Abstract: Background: WHO guidelines recommend the lateral flow urine lipoarabinomannan assay (LF-LAM) for TB diagnosis in hospitalised HIV-positive individuals. The role of LF-LAM among ambulant patients remains less well defined. We investigated the sensitivity of LF-LAM among ambulant HIV-positive adults in primary health clinics in South Africa. Methods: We enrolled adults (aged ≥18 y) with CD4 counts of ≤150 cells/mm 3 who had not received TB treatment or antiretroviral therapy in the preceding 3 or 6 mo, respectively. Research nurses performed the LF-LAM test on freshly voided urine. Results were compared with a reference standard of positive mycobacterial culture (sputum or urine). Results: Of 1505 (54.5% female; median age 37 y; median CD4 count 73 cells/mm 3 ) participants, 973 (64.7%) had a mycobacterial culture result; 105/973 (10.8%) were positive for Mycobacterium tuberculosis . LF-LAM sensitivity was 41.9% (95% CI 32.3 to 51.9%) and 19.0% (95% CI 12.0 to 27.9%) using grade 1+ and grade 2+ cut-off points, respectively. Sensitivity increased with severe immunosuppression and in the presence of poor prognostic indicators (low haemoglobin, body mass index). Conclusions: When used as the only TB diagnostic test, LF-LAM sensitivity is suboptimal, particularly using the grade 2+ cut-off. More sensitive tests for TB are needed that can be used in primary care settings.